Our BSTE section (Buy/Sell/Trade/Employ), where you can list a website for sale, is not currently available to non-members. You need to be not only a member but a member with 10+ posts.
Why? Because in the early days it was open to everyone and we were attracting all kinds of junk and spam. So we restricted it to only well trusted folk.
However, I've been working on solutions to this problem and we will be shortly accepting website listings from any registered member, even if they have zero posts!
There is no cost to listing, no success fee, no exclusivity clauses, no hoops to jump. Anybody who is registered simply agrees the terms and fills in the appropriate form to submit their website for sale.
If it's compliant, the listing will be approved and will show publicly in due course. I was initially going to set this section up in an auction format, but KenW3 and I (your two admins) have agreed that it's a bit demeaning for proper businesses to be subject to bids and counter bids in public. We also know how much of shill bidding goes on in marketplaces that allow public bidding ...and those marketplaces have no way of eliminating shill bidding. So, no auctions. Members can contact the seller by PM if they have any questions or wish to put in an offer.
This will hopefully open a good free avenue for anybody looking to sell their site and be of assistance to buyers looking for the better properties.
Update: July 22nd, 2012: Section now open for selling websites. No listing fee